JP4654708B2 - Image forming apparatus - Google Patents

Description

  The present invention relates to an image forming apparatus equipped with a plurality of image output apparatuses.

  2. Description of the Related Art Conventionally, in a registration control system (hereinafter referred to as “registon”) in an image forming apparatus equipped with a plurality of image output apparatuses, an image position recognition pattern predetermined by each ROS (Raster Optical Scanner) is arranged downstream of those ROSs. Sampling is performed by the arranged CCD, and the positional relationship of the sampling data is detected to determine how much the positional relationship is different from the positional relationship when it is assumed that there is no color shift of the image position recognition pattern of each color determined in advance. There has been proposed a method of providing a high quality image with little registration deviation by correcting the ROS writing timing or optical position based on the result of calculating the registration deviation amount of each color from the detected data.

  For example, in Patent Document 1, a mark is provided on a belt, and a sensor signal and an encoder signal that are generated every time the drive roll rotates are generated by a sensor and an encoder that detect the mark. Thus, the encoder pulse from the index signal to the sensor signal is counted, the value Ci and the time that the mark passes through the sensor are obtained, the belt speed fluctuation is calculated from the relationship, the belt surface speed is controlled, and the image Color misregistration in the forming apparatus is prevented.

However, due to the mounting error of the exposure device and sensor and the position variation of the exposure device and sensor due to the temperature fluctuation in the image forming apparatus, the photosensitive drum surface speed fluctuation due to the angular velocity fluctuation or eccentricity of the photosensitive drum is detected by the exposure position and sensor detection. Depending on the position, the speed fluctuation of the surface of the photosensitive drum at the exposure position cannot be accurately detected.
JP-A-6-263281

  In consideration of the above-described facts, an object of the present invention is to provide an image forming apparatus capable of accurately detecting the speed fluctuation of the drum surface at the exposure position.

Invention according to claim 1, in the image forming apparatus, an image bearing member for bearing a toner image is arranged along the axial direction of the image carrier, an exposure array for forming a latent image, before Kizo bearing A first pattern formed parallel to the axial direction of the image carrier outside the region where the latent image of the body is formed and provided at regular intervals along the circumferential direction; and the exposure array provided, variations in the first and reading sensor for reading the pattern information of the first pattern, the surface speed of the first pattern the image bearing member based on the pattern information read by the first reading sensor And a speed variation detecting means for detecting the position of the image carrier, and is arranged adjacent to the first pattern outside the region where the latent image of the image carrier is formed, and intersecting with the axial direction of the image carrier. The second provided at regular intervals along the circumferential direction A pattern, a second reading sensor that is provided integrally with the exposure array, is disposed adjacent to the first reading sensor, and reads pattern information of the second pattern, and is read by the second reading sensor. And position variation detecting means for detecting a position variation in the axial direction of the image carrier with respect to the exposure array based on the pattern information of the second pattern thus obtained.

According to the first aspect of the present invention, the exposure array arranged along the axial direction of the image carrier and forming a latent image, and the region of the image carrier where the latent image is formed, in the axial direction of the image carrier. And a first reading sensor that reads the pattern information of the first pattern that is formed in parallel to the image carrier and provided at regular intervals along the circumferential direction of the image carrier. Variation in the surface speed of the image carrier can be detected from the pattern information of the first pattern read by one reading sensor.

  By providing the exposure array and the first reading sensor integrally, the exposure array and the first reading sensor can be positioned as an absolute positional relationship. For this reason, for example, the positional relationship between the exposure array and the first reading sensor does not change due to, for example, the mounting error of the exposure array or the positional variation of the exposure array due to the temperature variation in the image forming apparatus.

  Accordingly, the surface speed of the image carrier at the exposure position along the circumferential direction of the image carrier can be accurately detected, and the detection accuracy can be improved. As a result, periodic fluctuations in the circumferential direction of the image carrier (so-called AC fluctuations). ) Correction accuracy is improved.

  In addition, since the distance between the exposure array and the image carrier is required to be mounted with high accuracy due to the limitation of the depth of focus (± 0.1 mm), by providing the exposure array and the first reading sensor integrally, The mounting accuracy of the first reading sensor with respect to the image carrier is also increased. For this reason, it is possible to adjust the depth of focus of the first reading sensor having the enlargement / reduction optical system with high accuracy, and to improve the detection accuracy.

Further, in a region outside a latent image on the image bearing member is formed, and a second pattern adjacent to the first pattern is arranged obliquely to the second pattern with respect to the axial direction of the image carrier And provided at regular intervals along the circumferential direction of the image carrier . A second reading sensor for reading the pattern information of the second pattern is provided integrally with the exposure array, and an image for the exposure array is obtained from the pattern information of the second pattern read by the second reading sensor by the position variation detecting means. A displacement in the axial direction of the carrier can be detected.

  Similarly to the detection of the periodic fluctuation in the circumferential direction of the image carrier, the exposure array and the second reading sensor are integrally provided so that the position of the exposure array and the second reading sensor can be changed due to the position fluctuation of the exposure array. The relationship never changes.

  Therefore, the axial variation of the image carrier relative to the exposure array can be accurately detected, and the detection accuracy is improved, and hence the correction accuracy of the periodic variation (so-called AC variation) in the axial direction of the image carrier is improved.

According to a second aspect of the present invention, in the image forming apparatus according to the first aspect, a first correction unit is provided that corrects the write timing of the exposure array based on the speed fluctuation detected by the speed fluctuation detection unit. It is characterized by that.

According to the second aspect of the present invention, the first correction unit corrects the writing timing of the exposure array on the basis of the detection result of the speed variation detection unit, so that the image due to the variation of the surface speed detected by the speed variation detection unit. The periodic fluctuation (AC fluctuation) in the circumferential direction of the image carrier can be corrected.

According to a third aspect of the present invention, in the image forming apparatus according to the first aspect, there is provided a second correction unit that corrects an angular velocity for driving the image carrier based on a speed variation detected by the speed variation detection unit. It is characterized by that.

In the invention described in claim 3, based on the detection result of the speed fluctuation detection means, the second correction means, by correcting the angular velocity of the image bearing member to calculate the angular velocity of the image bearing member, to claim 2 The same effects of the described invention can be obtained.

Invention according to claim 4, in the image forming apparatus according to claim 1, wherein the position based on the axial position change detected by the fluctuation detecting means, exposure of the exposure array in the axial direction of the photosensitive drum A third correction means for correcting the position is provided.

According to the fourth aspect of the present invention, based on the detection result of the speed variation detection means, the third correction means corrects the exposure position in the axial direction of the photosensitive drum of the exposure array, whereby the image carrier relative to the exposure position is corrected. The positional deviation in the axial direction can be corrected. In this case, the exposure position may be changed by changing the light emission position in the exposure array, or the position of the exposure array itself may be shifted along the axial direction of the image carrier.

According to a fifth aspect of the present invention, in the image forming apparatus according to the second or third aspect , a correction signal having a phase different from the speed fluctuation is generated based on the speed fluctuation detected by the speed fluctuation detecting unit. The correction is based on the correction signal.

According to the fifth aspect of the present invention, based on the detection result of the speed fluctuation detecting means, a correction signal having a phase different from the speed fluctuation of the surface of the image carrier is generated, and the speed fluctuation is corrected based on the correction signal. By doing so, the speed fluctuation of the surface of the image carrier is reduced.

According to a sixth aspect of the present invention, in the image forming apparatus according to the fourth aspect of the present invention, a correction signal having a phase different from the position variation is generated based on the position variation detected by the position variation detecting means, and the correction signal is generated. It is characterized by correcting based on the above.

According to the sixth aspect of the present invention, based on the detection result of the position fluctuation detecting means, a correction signal having a phase different from the position fluctuation in the axial direction of the image carrier is generated, and the position fluctuation is calculated based on the correction signal. By correcting, the position variation in the axial direction of the image carrier is reduced.

  Since the present invention is configured as described above, in the first aspect of the present invention, the exposure array and the first read sensor are integrally provided so that the exposure array and the first read sensor are in an absolute positional relationship. Therefore, it is possible to accurately detect the surface speed of the image carrier at the exposure position along the circumferential direction of the image carrier, and to improve the detection accuracy, and in turn, periodically in the circumferential direction of the image carrier. Correction accuracy of a large fluctuation (so-called AC fluctuation) is improved.

In addition , since the exposure array and the reading sensor are integrally provided, the positional relationship between the exposure array and the second reading sensor does not change due to the position variation of the exposure array. Directional fluctuations can be detected accurately, and detection accuracy can be improved. As a result, correction accuracy of periodic fluctuations in the axial direction of the image carrier (so-called AC fluctuations) can be improved.

According to the second and third aspects of the present invention, it is possible to correct periodic fluctuations (AC fluctuations) in the circumferential direction of the image carrier due to fluctuations in the surface velocity detected by the velocity fluctuation detector. According to the fourth aspect of the present invention, the positional deviation in the axial direction of the image carrier relative to the exposure position can be corrected.

According to the fifth aspect of the present invention, the speed fluctuation of the surface of the image carrier can be reduced. According to the sixth aspect of the present invention, the position variation in the axial direction of the image carrier can be reduced.

FIG. 1 shows a color image forming apparatus according to the implementation mode of the present invention.

  FIG. 1 is a schematic configuration diagram showing a tandem type digital color printer 10 as a color image forming apparatus according to Embodiment 1 of the present invention.

  Inside the digital color printer 10, image forming units 13Y, 13M, 13C, and 13K for each color of yellow (Y), magenta (M), cyan (C), and black (K) are horizontally arranged as image forming units. They are arranged at regular intervals along the direction. Note that Y, M, C, and K are omitted when it is not necessary to distinguish YMCK.

  Further, below the four image forming units 13Y, 13M, 13C, and 13K, an intermediate transfer belt 25 that transfers toner images of respective colors sequentially formed by these image forming units in a state of being superimposed on each other, It is arrange | positioned so that rotation is possible along the arrow direction.

  The toner images of each color transferred onto the intermediate transfer belt 25 in a multiple manner are collectively transferred onto a recording paper 34 as a recording medium fed from a paper feed tray 39 or the like, and then a fixing unit 37. Is fixed on the recording paper 34 and discharged to the outside.

  The four image forming units 13Y, 13M, 13C, and 13K are configured in the same manner except that the colors of the images to be formed are different, and are roughly divided into image carriers that rotate at a predetermined rotation speed in the direction of the arrow. Photoconductor drums 15Y, 15M, 15C, and 15K, scorotrons 12Y, 12M, 12C, and 12K for primary charging that uniformly charge the surfaces of the photoconductor drums 15Y, 15M, 15C, and 15K, and photoconductor drums Exposure images 14Y, 14M, 14C, and 14K are formed on the surfaces of 15Y, 15M, 15C, and 15K to form electrostatic latent images by exposing images corresponding to the respective colors, and formed on the photosensitive drums 15Y, 15M, 15C, and 15K. And a developing device 17 for developing the electrostatic latent image and a cleaning device 18.

Next, a description will be given main part of an image forming apparatus according to the implementation embodiments of the present invention. In addition, after demonstrating the reference example relevant to embodiment of this invention, embodiment of this invention is described.

  As shown in FIGS. 2 and 3, a line parallel to the axial direction of the photosensitive drum 15 is formed at one end side of the photosensitive drum 15 at a predetermined interval along the circumferential direction of the photosensitive drum 15. (Hereinafter referred to as a circumferential direction formation pattern 40).

  A circumferential direction reading sensor 42 is integrally provided at one end portion of the exposure array 14 located above the photosensitive drum 15, and faces a circumferential direction forming pattern 40 formed at one end portion of the photosensitive drum 15. Placed in position.

  As shown in FIG. 4, the circumferential direction reading sensor 42 includes a lens 44 that collects light and a light receiving unit 46 that receives reflected light, and is emitted by an LED (not shown). Light is condensed by the lens 44 onto the surface of the photosensitive drum 15 (so-called detection position, the central line P of the circumferential direction formation pattern 40 (see FIG. 3)), and reaches the surface of the photosensitive drum 15 and is reflected. Is incident on the light receiving unit 46.

  Since the photosensitive drum 15 is made of aluminum, the reflectance of light to the light receiving portion 46 is high in the portion where the circumferential direction forming pattern 40 is not formed. The reflected reflectance is low. For this reason, the presence or absence of the circumferential direction formation pattern 40 can be confirmed by the difference in the reflectance of light to the light receiving unit 46.

  Here, as shown in FIG. 5, the circumferential direction reading sensor 42 is connected to the control unit 48, and information read by the difference in reflectance reflected by the light receiving unit 46 (presence / absence of the circumferential direction forming pattern 40). Is input to the control unit 48 (step 100 shown in FIG. 6).

  As shown in FIG. 3 (FIG. 3 is a diagram in which the surface of the photosensitive drum 15 is developed in the circumferential direction), the circumferential direction formation pattern 40 is a predetermined shape along the circumferential direction of the photosensitive drum 15. Since they are formed at intervals, the presence or absence of the circumferential direction formation pattern 40 is detected alternately with the rotation of the photosensitive drum 15, but the circumferential direction formation is performed because the photosensitive drum 15 rotates at a constant rotational speed. The pattern 40 is detected at the same interval. The surface speed of the photosensitive drum 15 is detected based on the detected interval between the circumferential formation patterns 40 (step 102 shown in FIG. 6).

  Here, as shown in FIG. 2, by providing the exposure array 14 and the circumferential direction reading sensor 42 integrally, the exposure array 14 and the circumferential direction reading sensor 42 can be positioned as an absolute positional relationship.

  For this reason, for example, the positional relationship between the exposure array 14 and the circumferential direction reading sensor 42 changes due to the mounting error of the exposure array 14 or the position variation of the exposure array 14 due to the temperature variation in the digital color printer 10 (see FIG. 1). That's not true.

  Accordingly, the surface speed of the photosensitive drum 15 can be accurately detected along the circumferential direction of the photosensitive drum 15, and the detection accuracy is improved, and the correction accuracy of periodic fluctuations in the sub-scanning direction (so-called AC fluctuations) is improved. improves.

  Further, since the distance between the exposure array 14 and the photosensitive drum 15 is required to be mounted with high accuracy due to the limitation of the depth of focus (± 0.1 mm), the exposure array 14 and the circumferential direction reading sensor 42 are integrated with each other. By providing, the mounting accuracy of the circumferential direction reading sensor 42 to the photosensitive drum 15 is also increased. Therefore, it is possible to adjust the depth of focus of the circumferential direction reading sensor having the enlargement / reduction optical system (lens 44 (see FIG. 4)) with high accuracy, and to improve detection accuracy.

  On the other hand, FIG. 7A is a diagram in which the surface of the photosensitive drum 15 is developed along the circumferential direction, and the circumferential direction formation pattern 50 read by the circumferential direction reading sensor 42 is originally the circumferential position indicated by the design position. Although it should be the same interval as the direction formation pattern 52 (one-dot chain line), if the surface speed of the photosensitive drum 15 fluctuates due to eccentricity or the like, a deviation of Pe occurs with respect to the circumferential direction formation pattern 52 at the design position.

  In the controller 48, the surface speed fluctuation of the photosensitive drum 15 or the circumferential position fluctuation caused thereby is phased along the circumferential direction (arrow A direction) of the photosensitive drum 15, as shown in FIG. 7B. Calculation is made as data 54 (step 104 shown in FIG. 6), and antiphase data 56 that cancels out the phase data 54 is calculated (step 106 shown in FIG. 6).

  Incidentally, as shown in FIG. 5, the control unit 48 is connected to the exposure array 14, and is based on the antiphase data 56 with respect to the angular velocity variation calculated from the surface velocity variation of the photosensitive drum 15 calculated by the control unit 48. In addition, as the first correction means, the writing timing of the exposure array 14 is changed (step 108 shown in FIG. 6). Thereby, the fluctuation of the angular velocity of the photoconductor drum 15 can be canceled and the fluctuation can be reduced.

  Here, the circumferential direction reading sensor 42 is integrally provided at one end portion of the exposure array 14, but it is only necessary that the exposure array 14 and the circumferential direction reading sensor 42 can be positioned as an absolute positional relationship. This is not a limitation. For example, as shown in FIG. 8, the exposure array 14 and the circumferential direction reading sensor 42 may be fixed to a flat support member 58.

  Further, in this embodiment, the writing timing of the exposure array 14 is changed based on the antiphase data 56 with respect to the change in the angular velocity of the photosensitive drum 15, but it is only necessary that the change in the angular velocity of the photosensitive drum 15 can be reduced. This is not a limitation. For example, based on the antiphase data 56 with respect to the fluctuation of the angular velocity of the photosensitive drum 15, the rotation speed of the motor 60 connected to the photosensitive drum 15 is made variable as the second correction unit, and the angular velocity of the photosensitive drum 15 is changed. You may make it make a fluctuation | variation small.

Next, a description will be given main part of an image forming apparatus according to the implementation embodiments of the present invention. In addition, description is abbreviate | omitted about the content substantially the same as a reference example .

  As shown in FIGS. 9 and 10 (FIG. 10 is a diagram in which the surface of the photosensitive drum 15 is developed in the circumferential direction), the circumferential direction forming pattern 40 is formed on one end side of the photosensitive drum 15. In addition, an axial direction forming pattern 62 is formed on the inner side of the circumferential direction forming pattern 40 so as to be inclined with respect to the axial direction of the photosensitive drum 15, and is arranged at predetermined intervals along the circumferential direction of the photosensitive drum 15. ing.

  On the other hand, a circumferential direction reading sensor 42 and an axial direction reading sensor 64 are integrally provided at one end of the exposure array 14, and are arranged so as to face the circumferential direction forming pattern 40 and the axial direction forming pattern 62, respectively. Along with the variation (rotational direction deviation) of the angular velocity of the body drum 15, the axial deviation of the photosensitive drum 15 can also be detected. Here, since the configuration of the axial direction reading sensor 64 is the same as that of the circumferential direction reading sensor 42, description thereof is omitted.

  FIG. 11 is a developed view of the surface of the photosensitive drum 15 along the circumferential direction. The axial direction formation pattern 66 read by the axial direction reading sensor 64 is originally an axial direction formation pattern 62 (shown at the design position). However, when the position of the photosensitive drum 15 in the axial direction differs in the circumferential direction of the photosensitive drum 15 due to an attachment error or the like, Xe with respect to the axial formation pattern 62 at the design position. Deviation occurs.

  However, since this deviation (Xe) includes a deviation (Pe) due to the angular velocity fluctuation of the photosensitive drum 15, the deviation (Le) of the axial direction formation pattern 66 is different from the axial direction formation pattern 62 at the design position. The value is obtained by subtracting the circumferential displacement (Pe (see FIG. 7A)) of the photosensitive drum 15 due to the angular velocity fluctuation from (Xe). The axial displacement of the photosensitive drum 15 can be calculated based on the displacement amount Le.

  Here, as shown in FIGS. 9 and 10, the exposure array 14, the circumferential direction reading sensor 42, and the axial direction reading sensor 64 are integrally provided, so that the exposure array 14, the circumferential direction reading sensor 42, and the axial direction reading sensor 64 are provided. 64 can be positioned as an absolute positional relationship.

  Therefore, the positional relationship between the exposure array 14, the circumferential direction reading sensor 42, and the axial direction reading sensor 64 does not change due to the position variation of the exposure array 14. Therefore, the angular velocity and the axial position of the photosensitive drum 15 can be accurately calculated along the circumferential direction of the photosensitive drum 15, and the detection accuracy can be improved. As a result, periodic fluctuations in the main scanning direction and the sub scanning direction ( Correction accuracy of so-called AC fluctuation is improved.

  That is, the control unit 48 calculates the angular velocity and the axial deviation of the photosensitive drum 15 as the phase data 54 along the circumferential direction of the photosensitive drum 15, and calculates the reverse phase data 56 that cancels out the phase data 54. To do.

  The write timing of the exposure array 14 is changed based on the antiphase data 56 with respect to the change in the angular velocity of the photosensitive drum 15 calculated by the control unit 48, and the axial direction of the photosensitive drum 15 calculated by the control unit 48 is changed. As shown in FIGS. 12A to 12C, the range of the LED 68 to be used is changed on the basis of the reverse phase data with respect to the deviation, and the writing position (indicated by a black circle) of the exposure array 14 is used as the third correction means. I try to change it.

  As a result, it is possible to cancel the fluctuation of the angular velocity of the photosensitive drum 15 to reduce the fluctuation, and to cancel the deviation in the axial direction of the photosensitive drum 15 to reduce the deviation.

  In addition, this form is an Example to the last, and it cannot be overemphasized that it can change suitably in the range which does not deviate from the main point of this invention.

  In the present embodiment, the writing position of the exposure array 14 is changed based on the reverse phase data with respect to the axial displacement of the photosensitive drum 15, but it is sufficient if the axial displacement of the photosensitive drum 15 can be reduced. Therefore, it is not limited to this.

  For example, the exposure array 14 itself may be movable along the axial direction of the photosensitive drum 15. Specifically, as shown in FIG. 13, a piezoelectric element 70 connected to the control unit 48 is disposed at the other end of the exposure array 14, and an end of a piezoelectric holding member 71 that holds the piezoelectric element 70 is provided. Fix to the fixing member 73. For this reason, when a voltage is applied to the piezoelectric element 70, the piezoelectric element 70 is bent and deformed toward the exposure array 14 side. The exposure array 14 may be moved along the axial direction of the photosensitive drum 15 according to the amount of deformation of the piezoelectric element 70.

  As shown in FIG. 14, a ball screw 74 connected to a motor 72 connected to the control unit 48 is screwed into a nut 75 on the exposure array 14 side at the other end of the exposure array 14. 74 may be rotated, and the exposure array 14 may be moved along the axial direction of the photosensitive drum 15 via the nut 75.

  Further, as shown in FIG. 15, a rack 76 is extended to the other end of the exposure array 14, and a pinion 80 connected to a motor 78 connected to the control unit 48 is engaged with the rack 76 so that the motor The exposure array 14 may be moved along the axial direction of the photosensitive drum 15 through the pinion 80 and the rack 76 by the rotation of 78.

In the reference example , as shown in FIGS. 2 and 3, the circumferential direction reading sensor 42 is used to collect light on the center line P of the circumferential direction forming pattern 40, but FIGS. 16 and 17 ( A) (FIG. 17A is a diagram in which the surface of the photoconductive drum 15 is developed in the circumferential direction.) Using the CCD sensor 82, the circumferential direction formation pattern 40 and the circumferential direction formation pattern are as shown in FIG. The axial direction forming pattern 84 formed along the circumferential direction at a predetermined position in the axial direction of the photosensitive drum 15 outside the 40 may be read as image data.

  Further, in this case, since the reading area is widened, even if the axial direction forming pattern 84 is a straight line along the circumferential direction of the photosensitive drum 15, the amount of deviation from the reading reference line Q is obtained, thereby obtaining the photosensitive drum 15. The axial displacement amount δ (see FIG. 17B) can be detected.

  Furthermore, in this embodiment, for example, the angular velocity of the photosensitive drum 15 is calculated as the phase data 54 along the circumferential direction of the photosensitive drum 15, and the reverse phase data 56 that cancels out the phase data 54 is calculated. Although the variation of the angular velocity of the photosensitive drum 15 is reduced, it is only necessary to reduce the variation of the angular velocity of the photosensitive drum 15, so that the method is not limited to this method.

  On the other hand, FIG. 18 and FIG. 19 show an example of correcting the surface speed fluctuation caused by the eccentricity of the photosensitive drum 15 in real time. Since the surface speed fluctuation due to eccentricity is the same fluctuation at the same position of the photosensitive drum 15, the circumferential reading sensor 42 and the exposure array 14 shift the position of the photosensitive drum 15 in the circumferential direction, and the speed immediately before the exposure. The fluctuation is detected by the circumferential direction reading sensor 42, and the exposure timing for exposing the photosensitive drum 15 is corrected based on the detected result.

1 is a schematic diagram illustrating an image forming apparatus according to an embodiment of the present invention. It is a perspective view which shows the exposure array and circumferential direction reading sensor of the image forming apparatus which concern on the reference example of this invention. It is the figure which developed the exposure array of the image forming apparatus which concerns on the reference example of this invention, the circumferential direction reading sensor, and the surface of the photoreceptor drum along the circumferential direction. It is a conceptual diagram which shows the structure of the circumferential direction reading sensor of the image forming apparatus which concerns on the reference example of this invention. FIG. 4 is a block diagram illustrating a relationship among a control unit, an exposure array, and a circumferential direction reading sensor of an image forming apparatus according to a reference example of the present invention. 6 is a flowchart illustrating an operation of the image forming apparatus according to the reference example of the present invention. (A) is a figure explaining the fluctuation | variation of the angular velocity of the photosensitive drum which developed the surface of the photosensitive drum of the image forming apparatus which concerns on the reference example of this invention along the circumferential direction, (B) is photosensitive. It is explanatory drawing which correct | amends the fluctuation | variation of the angular velocity of a body drum. It is a perspective view which shows the modification of the exposure array of the image forming apparatus which concerns on the reference example of this invention, and the circumferential direction reading sensor. 1 is a perspective view showing an exposure array and a circumferential direction reading sensor of an image forming apparatus according to an embodiment of the present invention. FIG. 3 is a diagram in which the exposure array, the circumferential direction reading sensor, and the surface of the photosensitive drum of the image forming apparatus according to the embodiment of the present invention are developed along the circumferential direction. FIG. 4 is a diagram illustrating an axial shift of the photosensitive drum in which the surface of the photosensitive drum of the image forming apparatus according to the embodiment of the present invention is developed along the circumferential direction. (A)-(C) are explanatory drawings which correct | amend the shift | offset | difference of the axial direction of a photoconductive drum. FIG. 10 is a perspective view showing a first modification that corrects an axial shift of the photosensitive drum. It is a perspective view which shows the 2nd modification which correct | amends the shift | offset | difference of the axial direction of a photoconductive drum. It is a perspective view which shows the 3rd modification which correct | amends the shift | offset | difference of the axial direction of a photoconductive drum. It is a perspective view which shows the modification of the circumferential direction reading sensor. (A) is the figure which developed the surface of the photosensitive drum of FIG. 16 along the circumferential direction, (B) is a figure explaining the shift | offset | difference of the axial direction of a photosensitive drum. FIG. 5 is a perspective view illustrating a method for correcting a deviation in the circumferential direction of the photosensitive drum in real time. FIG. 19 is a developed view of the surface of the photosensitive drum in FIG. 18 along the circumferential direction.

Explanation of symbols

10 Digital color printer (image forming device)
14 exposure array 15 photosensitive drum 40 circumferential direction formation pattern (first pattern, third pattern)
42 circumferential direction reading sensor (first reading sensor)
48 control unit (speed fluctuation detection means, position fluctuation detection means, detection means, correction means)
50 circumferential direction formation pattern (first pattern)
52 circumferential direction forming pattern 54 phase data 56 reverse phase data 60 motor (second correction means)
62 Axial direction forming pattern 64 Axial direction reading sensor (second reading sensor)
66 Axial direction formation pattern (second pattern)
70 Piezoelectric element (third correcting means)
72 Motor (third correction means)
74 Ball screw (third correction means)
75 nut (third correction means)
76 racks (third correction means)
78 Motor (third correction means)
80 pinion (third correction means)
82 CCD sensor (image sensor)
84 Axial direction formation pattern (third pattern)

Claims (6)

An image carrier for carrying a toner image;
An exposure array disposed along the axial direction of the image carrier to form a latent image;
Outside a region in which a latent image before Kizo carrier is formed, formed parallel to the axial direction of said image bearing member, a first pattern provided at regular intervals along the circumferential direction,
A first reading sensor provided integrally with the exposure array and reading pattern information of the first pattern ;
Speed fluctuation detecting means for detecting fluctuations in the surface speed of the image carrier based on pattern information of the first pattern read by the first reading sensor;
Outside the region where the latent image of the image carrier is formed, it is arranged adjacent to the first pattern and intersects with the axial direction of the image carrier, and in the circumferential direction of the image carrier A second pattern provided at regular intervals along,
A second reading sensor provided integrally with the exposure array, disposed adjacent to the first reading sensor, and reading pattern information of the second pattern;
Position variation detecting means for detecting a position variation in the axial direction of the image carrier relative to the exposure array based on pattern information of a second pattern read by the second reading sensor;
An image forming apparatus comprising: The image forming apparatus according to claim 1, further comprising a first correction unit configured to correct a writing timing of the exposure array based on a speed variation detected by the speed variation detection unit. The image forming apparatus according to claim 1, wherein the second correcting means for correcting the angular velocity of driving the image bearing member on the basis of the speed variation detected by the speed fluctuation detection means is provided. Wherein based on the position variation axial position change detected by the detection means, according to claim 1, characterized in that third correction means for correcting the exposure position of the exposure array in the axial direction of the photosensitive drum is provided The image forming apparatus described in 1. 4. The image formation according to claim 2, wherein a correction signal having a phase different from that of the speed fluctuation is generated based on the speed fluctuation detected by the speed fluctuation detecting unit, and the correction signal is corrected based on the correction signal. apparatus. 5. The image forming apparatus according to claim 4 , wherein a correction signal having a phase different from that of the position fluctuation is generated based on the position fluctuation detected by the position fluctuation detecting unit, and correction is performed based on the correction signal.

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